Steerable guide catheters provide a number of advantages over fixed guide catheters. Steerable guide catheters reduce procedural time. Because physicians can shape the device in real time to conform to the patient's anatomy they can quickly achieve the access they would like and enable the guide catheter to conform to the presenting anatomy. This prevents physicians from exchanging guide catheters to find one which works and such exchange involves additional product costs for each device, takes more time, and increases procedure risk as physicians manipulate more devices within patient anatomy.
Steerable guide catheters also provide more control. More control with such devices should equate to better outcomes as well. This is well described in the literature for carotid access. Carotid stenting trial data suggests that 40 percent of the strokes in these trials are due to emboli dislodged in the non-target vessel. This suggests that the manipulation which occurs during carotid access in the aorta is responsible for this—and thus responsible for 40% of the strokes which occurred. This is significant as other aorto ostial manipulations with fixed catheters are very similar to this. A steerable guide catheter that requires less manipulation to gain access to the target vessel and does not scrape the arterial wall as its curved portion is dragged along and flipped within the vasculature as it goes in straight over a wire is likely to significantly improve patient outcomes through more control and increase patient safety by limiting manipulations. Radial and brachial artery access using steerable endoluminal devices for cardiac and peripheral procedures is highly desirable due to the significant cost savings that would result from such procedures as compared to procedures performed via femoral access.
As devices can be advanced straight into the vascular space and then deflected to conform to a shape, they enable the distal end to have superior back up support in its deflected configuration than one can achieve with any sort of preformed catheter which must have a very flexible distal end as in its advancement and retraction within the vasculature, as a pre-shaped guide, it is likely to scrape the arterial wall and if too stiff could cause damage.
Steerable guide devices can be customized to the presenting anatomy; a physician can have exactly the desired curve shape and not aim for something in his current inventory that is close to the presenting anatomy. If a second catheter device (wire, balloon, atherectomy device, CTO device, stent etc.) inserted through a steerable introducer or steerable guide device changes the shape of the latter device it may be formed with the other device in place to provide the exact shape desired. This is not possible with fixed guides.
The difficulty in designing and manufacturing such devices is that the mechanisms to enable steering are complex and require real estate for their engineering. This adds a requirement of increased thickness to the catheter walls. Increased catheter wall thickness is a significant disadvantage as it requires a larger hole and larger access vessel to do procedures for a given therapeutic device such as a filter, wire, balloon, stent, coil, vascular graft, atherectomy, lasers, valve, snare, aspiration catheter or drug delivery system. The complexity of the mechanism also adds to the cost of the devices which compete with standard fixed guide shapes which have become a commodity. For these reasons, these devices are new in the marketplace.
These same issues are relevant for steerable introducers or steerable sheaths that enter the body percutaneously and do not require external introducers such as a guide or a steerable guide catheter does. A steerable introducer adds additional design requirements in that it must be more trackable and flexible to navigate tortuous anatomy like a sheath, but must have column strength to support the forces applied by pull wires or tendons used to deflect the deflection mechanism, and it must be able to transmit torque, which most sheaths do not do well, to enable it to be used to guide interventions with its shapeable distal end. Additionally, with the increasing demand in interventional cardiology for specifically shaped devices for accessing the coronary arteries, carotid artery, renal arteries, the atria and ventricles of the heart, femoral arteries and the like, a steerable introducer with preformed shape to enable such access would be highly desirable.
There remains a need to improve steerable endoluminal devices.